If the US federal government shuts down at midnight on Friday, medical marijuana patients and providers will suddenly be at risk of being arrested, prosecuted, and sent to prison by Jeff Sessions’ Justice Department. Here’s why:

An existing budget provision, the Rohrabacher-Blumenauer amendment prevents the Drug Enforcement Administration (DEA) and other agencies from spending money to interfere with state medical cannabis laws. Under a government shutdown scenario, this protection would expire, but federal drug enforcement and prosecution actions, which are exempted from furloughs, would continue.

Why Might The Government Shut Down?

A bill to extend federal funding levels and policy riders like the marijuana one through February 16 was approved by the House on Thursday. But a heated dispute over immigration issues has jeopardized its passage in the Senate, where a significant number of Democrats are refusing to support any bill that does not provide protections to people who were brought to the U.S. as children.

Earlier this month, Attorney General Sessions rescinded Obama-era guidance that has generally allowed states to implement their own cannabis laws without federal intervention. That has left recreational marijuana businesses and consumers without a key protection they’ve relied on since 2013, but the ongoing existence of the medical cannabis spending rider has continued to keep patients and providers safeguarded from federal attacks.

Until now.

An unintended consequence of Senate Democrats’ move to block the funding extension bill and shut down the government over immigration issues is that medical marijuana patients and industry operators would be at much greater risk, as soon as this weekend.

Why Would Drug Enforcement Continue Under A Shutdown?

“All agents in DEA field organizations are excepted from furlough because they support active counternarcotics investigations. This encompasses 21 domestic divisions, 7 regional foreign divisions, critical tactical support groups including the El Paso Intelligence Center and the Special Operations Division, forensic sciences, and technical surveillance support,” a Justice Department shutdown contingency plan says. “DEA investigations need to continue uninterrupted so that cases are not compromised and the health and safety of the American public is not placed at risk.”

The same goes for federal prosecutors.

“As Presidential Appointees, U.S. Attorneys are not subject to furlough,” the shutdown document reads. “Excepted employees are needed to address ongoing criminal matters and civil matters of urgency throughout the Nation. Criminal litigation will continue without interruption as an excepted activity to maintain the safety of human life and the protection of property.”

Politics Of Marijuana And Immigration Collide

Democrats, especially those considering 2020 presidential bids, are facing enormous pressure from their progressive base not to go along with yet another bill in a series of short-term funding extensions that do not include protections for young immigrants known as “DREAMers.” Because Republicans hold only 51 seats in the chamber, and a handful of GOP members are also opposing the spending resolution, leaders need support from Democrats to reach the critical 60-vote threshold to advance legislation.

The medical cannabis budget rider was first enacted into law in late 2014, and has since been extended for each subsequent fiscal year. Last May, Sessions sent a letter to congressional leaders asking them not to continue the medical marijuana rider into Fiscal Year 2018.

“I believe it would be unwise for Congress to restrict the discretion of the Department to fund particular prosecutions, particularly in the midst of an historic drug epidemic and potentially long-term uptick in violent crime,” he wrote. “The Department must be in a position to use all laws available to combat the transnational drug organizations and dangerous drug traffickers who threaten American lives.”

Setting aside the important question of whether the medical cannabis rider will be included in full Fiscal Year 2018 spending legislation that congressional leaders continue to negotiate — and it is a big question, since House leaders blocked lawmakers from even voting on whether to include the policy in that chamber’s version of Justice Department spending legislation — the current budget brinksmanship on Capitol Hill means the medical marijuana protections could disappear as soon as Saturday morning.